code: def update(self, colors=None):
      if colors is not None and self._cached_colors is not None:
          self._current_colors = self._compute_over(
              self._cached_colors, colors
          )
      else:
          (
              self._current_colors,
              self._cached_colors,
          ) = self._compose_overlays()
      self._apply()
  
file_path: mne-python/mne/viz/_3d_overlay.py
imports: from collections import OrderedDict
  import numpy
  from ..utils import logger
label_desc: Use image node_id 8 for calling the _LayeredMesh obj's underlying member method code with example usage: obj.update(colors) without return types